Patent GB-1469538-A (GB)
Title: Television display systems
IPC: H01J37/22
Filed: 1974-06-17
Abstract: 1469538 Scanning electron microscope; radiography SIEMENS AG 17 June 1974 [25 June 19731 26701/74 Heading H4F A (colour) cathode-ray tube television monitor operating at standard scanning rate is employed to display information derived from a scanner unit which scans an object relatively slowly, e.g. a scanning electron microscope or the scanner unit in a particle radiation measuring instrument. Fig. 1, shows one embodiment in which the scanner unit is a scanning electron microscope 1 the X-deflection (i.e. line scan) of which is controlled by a sawtooth generator 7 of period t 1 =20 m. sec. which is the same as that T2 of the field deflection generator 16 of a conventional colour television monitor display tube 14 both generators being synchronized by a 50 Hz mains supply 9. The period t 2  of the line scan generator 15 for the monitor display has the conventional value 64 Á sec. whilst the pariod T 1  of the frame scan (Y) generator 8 of the electron microscope is a multiple of t 1  such generator being controlled by a trigger 10 to stop after one complete sweep of the object 4 scanned by the beam. When object 4 is impacted by the electron beam X-rays are generated some of which are incident on an energy-dispersing X- ray semi-conductor detector 11 where they trigger voltage pulses supplied as input to an amplifier 12. The output of the latter is supplied to an amplitude analyser 13 comprising three gates TORI ... TOR3 each of which is adjusted to pass only pulses corresponding to a specific chemical element in the object to a respective one of three "integrating pulsers" 19 each of which produces an output A on the occurrence of a trigger pulse at input T assuming that at least one pulse at input at E (from analyser 13) has arrived since the occurrence of the previous trigger at input T. The trigger pulses are produced by a comparator on amplitude equality of the Y scan sawtooth from generator 8 and the X<SP>1</SP> scan sawtooth from generator 15 and at the occurrence of each trigger output the R (red), G (green) and B (blue) guns of the monitor are unblanked so that each line scanned on the object is reproduced as a vertical line 18 on the monitor screen the distance # of the latter line from the edge of the display being proportional to the distance of the scanning line on object 4 from the first scanning line on the object. Thus as the beam 3 sweeps over the latter the line 18 moves towards the right hand side of the display. Fig. 2, shows a second embodiment in which the scanner unit is a particle radiation measuring instrument which employs a mechanically controlled scanning system 20 to scan an area F which may be part of the surface of the body of a patient to whom a radio-active preparation such as I128 has been administered for diagnostic purposes. The X deflection is controlled by a generator 27 the (line) period t 1  of which is such that the time of scanning one "image point" is equal to the field period or a whole number multiple thereof of the television display monitor and the Y deflection is controlled by a generator 8 the period T 1  of which is a whole number multiple of t 1 , the scanning being controlled by a trigger 10 to effect a single sweep. In operation the scanning system moves a blocking layer semi-conductor detector 21 in which each incident particle triggers a voltage pulse, the number of pulses triggered per unit time being proportional to the intensity of the radiation examined. These pulses are summed in a counter 28 which in response to an input from an AND gate 24 responsive to equality of both the X and X<SP>1</SP> and of the Y and Y<SP>1</SP> sawtooth waves in respective comparators 22, 23, passes its count to a signal-colour converter 29 and then resets. The converter converts the output from counter 28 into a combination of colour signals determined by the magnitude of the counter signal and supplies such colour signals to intensity modulate the beam of monitor tube 14. With the periods T 1  and t 1  having the valves indicated above bright-up of the monitor tube beam in each field period T 2  will occur only at that point 26 whose co-ordinates correspond with the co-ordinates of the scanned point 25. The detector 21 may be replaced by an infrared detector when it is required to record the thermal radiation relief of a surface the output of the detector, comprising a voltage having a magnitude proportional to the intensity of the radiation, being converted to digital form and then processed by the counter 28 and converter 29. Instead of moving the detector in a raster scan pattern the detector may be fixed and scanning may be effected by employing mechanically displaced mirrors.